In recent years, at conjunction with more abstract conception being required, flexible behavior is being treated as necessary in artificial intelligence employed in games. Conventionally, artificial intelligence in games has been developed with either a finite state machine (hereinafter FSM) or a behavior tree (hereinafter BT).
An FSM, as illustrated in FIG. 1, is configured such that states are made to be nodes, and these nodes are connected by transition lines; when an event occurs, a transition is made to the node that corresponds to that event, and the state corresponding to the node that is transitioned to is made to be the state of the character. Meanwhile, a BT is a tree representation of character action rules, and, as illustrated in FIG. 2, for example, defines which of child nodes (actions A-C) to execute and/or in what order to execute them depending on a parent node. In general, the FSM is superior for fixed control, and the BT is superior for on the fly control.